Push Notification "Change Events"

For Push Notifications, in the documentation, it says a possible event code could be “change – some aspect of the flight plan has been modified, such as a departure time delay or a gate change.”. This, I assume, could be used to get notifications if a flight has been delayed. However, when testing and registering notifications, the change event type is never registered as a channel or ever sent. Why is this?

Also, will there be major improvements for push notifications in terms of pricing or features FXML 3.0?